Recent evidence suggests that granulosa cell differentiation is associated with changes in content of receptors for specific hormones (estradiol, FSH, and LH), and that the action of one hormone may influence the amount of receptor for another hormone: estradiol acts to increase FSH binding to granulosa cells; FSH acts to increase LH receptor and decrease estradiol receptor in granulosa cells. The objective of this project will be to study the action of FSH on granulosa cell differentiation. The specific aims and approaches are: (1) to establish and characterize a model system, the estradiol-treated, hypophysectomized rat, for studying FSH action; (2) to determine the functional relationships between FSH binding, adenylate cyclase and progesterone production; and (3) to determine some of the effects of FSH on synthesis, glycosylation and phosphorylation of plasma membrane proteins (including LH receptor) during granulosa cell differentiation.